How to count: an introduction to combinatorics

What's It All About? What Is Combinatorics? Classic Problems What You Need to Know Are You Sitting Comfortably? Permutations and Combinations The Combinatorial Approach Permutations CombinationsApplications to Probability Problems The Multinomial Theorem Permutations and Cycles Occupancy Problems Counting the Solutions of Equations New Problems from Old A ""Reduction"" Theorem for the Stirling Numbers The Inclusion-Exclusion Principle Double Counting Derangements A Formula for the Stirling NumbersStirling and Catalan Numbers Stirling Numbers Permutations and Stirling Numbers Catalan Numbers Pa